Problem: $ { \left[\begin{array}{rr}{3} & {4} \\ {-1} & {-1} \\ {1} & {-2}\end{array}\right]-\left[\begin{array}{rr}{3} & {-2} \\ {4} & {2} \\ {-2} & {-1}\end{array}\right] = {?} } $
To find the difference of two matrices, subtract the corresponding items between each matrix. ${\left[\begin{array}{rr}{3}-{3} & {4}-{-2} \\ {-1}-{4} & {-1}-{2} \\ {1}-{-2} & {-2}-{-1}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{0} & {6} \\ {-5} & {-3} \\ {3} & {-1}\end{array}\right]}$